The present invention relates to cooling of equipment in cabinets and more particularly to integrate the cabinet cooling into a raised floor or overhead cooling system.
It has been found that cabinet cooling systems that are not integrated with a fault tolerant, concurrently maintainable and transparently expandable design of a raised floor or overhead cooling system cannot reasonably control overheating of equipment. The heat produced in some of the higher technology systems exceeds the capacity of systems currently available resulting in damage to high-tech computers and peripheral equipment.
Often, expensive, quality uninterruptable power systems (UPS) are installed for both the computer systems and cabinet fan powered cooling assemblies. Existing cabinet cooling technologies, waste available UPS power because methods do not exist to vary the fan energy as a percentage of the power required to cool the critical computer and other electronic equipment installed in the cabinets. Additionally, the typical cabinet fan is non-redundant and is sized to cool the maximum load projected for the cabinet, even though the average cabinet may only contain a fraction of the heat producing equipment that was considered for the fan selection.
A major problem develops in those systems which are initially sufficient to handle the heat loads expected, but must have cooling capacity increased without disturbing the installed heat producing equipment. There are many industries that cannot readily accept down time of equipment to accommodate changes; such as, railroads, production line control systems, financial markets, air travel reservation centers and the like.
Another problem is the industry practice to provide cuts in a raised floor that are left open with only a few square inches containing any cables or wires. Cooling air is drained from the raised floor unimpeded through the excessive cable openings, resulting in loss of air and static pressure that is needed for cooling elements or equipment in the cabinet overhead cooling is distributed from overhead ducts and the problem is that the room becomes cold, thus reducing the capacity of the cooling system.
In a large number of large installations, cabinets are set side-by-side with no walls in-between. The entire interior area thus created is treated in many respects as a single entity resulting in large amounts of fans used in the aggregate and wasted critical power. In these installations a fan or perhaps two are located in the top wall of the cabinets and may be programmed to a fixed speed. A cabinet with a large heat load may be positioned next to a cabinet with a small heat load and yet the fan associated with this later cabinet may be running at full speed. The usual procedure in such systems because there are separations between cabinets is to run with fans at a standard speed regardless of load which is very wasteful of critical power. It is to be noted that power is supplied for the computer and at most 10% should be used for cooling. Thus, every effort should be made to conserve power used for cooling.
The installations previously provided required the tiles of elevated floors to be cut at a cost of approximately $100/tile to accommodate the cabinets and provide adequate support. The cutting of the tiles, usually on the job, is time consuming and quite expensive. No attempt has been made to date to provide appropriate material to accommodate the floor to the cabinets or the cabinets to the floor.
Large losses of cooling energy are encountered through openings through which cables and wires are introduced into the cabinets. Inadequate use of masking or structural features to provide shielding is the rule.
An important failure of the prior systems is their failure to permit the system to be readily adjusted in the field to the environment. Openings cut in the field that were large enough for installers to work through, pull wires, etc. were grossly oversized for cooling. In many cases the cabinets were pre-wired and left unpowered, waiting months for operating load to materialize, yet the openings left by installers would not be closed. Any and all of the air passing through these access openings under the floor wasted cooling capacity and static pressure. They failed to a great extent to control properly cooling capacity, static pressure and to the extent controllable under very difficult procedures, often requiring a cabinet to be unloaded and tipped over for effecting control. The wasted cooling capacity issues could not be resolved even if other critical systems were adversely affected because the need for continuous data and telecommunications processing prevented any interruption to the operation of equipment in working cabinets. Retrofitting existing cabinets with on-line processing load is nearly impossible to accomplish without risk. Such latter procedure relates to the cooling capacity and pressure under tile floors and the need to insure, once installed, that each cabinet drain off minimum cooling air and produce minimum pressure drop.
It is an object of the present invention to avoid the necessity of custom cutting of floor tiles to accommodate equipment cabinets.
Another object of the invention is to employ barriers between cabinets to avoid interaction of cooling effects.
It is yet another object of the invention to provide equipment that permits convection cooling of components in a cabinet to reduce or eliminate the need for critical electrical power to operate cabinet cooling fans, or use forced cool air cooling or use of both types of cooling concurrently.
Yet another object of the invention is to provide members in the interior of a cabinet that prevent interference with the flow of cooling air from under the floor on which the cabinets are situated and members that prevent interface with flow into or out of the top of a cabinet.
It is still another object of the invention to permit cabinets having different power loads to be situated side-by-side without causing a cooling capacity conflict between adjacent cabinets.
An object of the invention is to control distribution of static pressure and cooling air from under the floor on which the cabinet is standing.
Another object of the invention is to be able to provide multiple installed fans where needed and to control the operation of the fans including disabling some or all to maintain a desired temperature.
Another object is to use fans that are small enough in size to allow multiple fans to fit on the top or the bottom of a standard sized cabinet for adequate capacity control, limiting the use of critical power yet still providing redundant fan operation.
Still another object of the invention is to provide visual and/or audible indications of the conditions in a cabinet.
Another object is to provide a network connection to monitor the cabinet cooling performance across a local area network (LAN), wide area network (WAN) or the Internet.
It is an object of the invention to prevent leakage of air to be used in cooling around cables bringing in power or control signals.
Still another object is to provide a method of field adjusting the wireway openings so that a cabinet can sit empty without wasting cooling airflow or static pressure, as the wireways remain closed while allowing easy field adjustments for wire and airflow once electronic equipment is installed into the cabinet.
Another object of the invention is to limit the use of critical power to that actually required to maintain temperature.
It is still another object of the invention to be able to accommodate vastly different cooling loads in adjacent cabinets.
Yet another object of the invention is to provide in the top of the cabinet accommodations for a plurality of panels that may accommodate fans, be blank panels, be panels for connection to forced air cooling supplies or large exhaust systems and highly perforated panels permitting ready air flow therethrough.
The cabinet of the present invention has a top surface that can accommodate multiple insertable panels that may be blank plates, highly perforated laces, variable opening grommets, pipes to accept cooling, or exhaust air and/or fans. Multiple induction fans may be used and allow paralleling of the capacity incrementally to provide redundant fan operation as needed, while limiting UPS power. The bottom surface of the cabinet sits on tiles of a raised floor in one embodiment over an opening and has multiple adjustable grommets to control flow of cool air into the cabinet as needed. The shelves in the cabinet are all highly perforated, while simultaneously fabricated for adequate structural support, so that cool or ambient air may readily flow through the cabinet and out of the top. The door and perhaps back panel of the cabinet may also have controlled perforated regions. A highly perforated shelf installed at the factory is positioned a distance above the floor to prevent any equipment to be placed under the shelf so that flow through the grommets is not impeded. Cooling can also be provided by overhead ducts, but with the degree of cooling required for cabinets containing equipment that creates high temperatures, the room itself would be far too cool for comfort. A solution to the use of overhead ducts for cooling is to direct the cool air through small distribution ducts directly into the cabinets.
The cooling mechanism employed does not rely heavily on the pressurized air from under the floor. The mechanism relies in most instances on room air drawn into the cabinet by convection and/or a fan or fans located on the top of the cabinet. The cabinet resembles a stack with both convection currents and the fan inducing the air heated by the equipment to flow out of the top of the cabinet. In many instances the convection currents are sufficient to cool the equipment and the fan are used to break up conflicting convection flow patterns. The fan insures that the air flows around all of the equipment to carry off the heat. This feature is assisted by highly perforated shelves. If necessary, cooling air from under the floor may be admitted to the cabinet through grommets in the bottom of the cabinet controlling such flow. The flow of pressurized cool air into the cabinet is limited to that necessary to affect the desired cooling so as not to overload and possibly burn up the air conditioners supplying cool air under the floor.
The stack effect of the cabinets causes the heated air to rise well above the cabinets so that hot air exiting one cabinet does not flow around the air intake region of adjacent cabinets.
A slide damper in the door is held in an open, partially open, or closed position by nylon or other plastic non-electrically conductive hardware so that if screws, fasteners, plugs, etc. break loose as a result of vibration or use of the damper electrical equipment is not damaged. Also, the damper is fail safe; that is, if the screws, plugs, etc. holding the damper in a fully closed or partially open position, the damper fully opens and the equipment will not overheat. Further, the hardware employed is captive hardware such that only broken parts can fall in the cabinet. Under normal circumstances there are no loose parts. All components of the physical system are available from outside the cabinet so that tools are not required to be introduced into the cabinet eliminating the danger of damage to the equipment terminals or wires from the tools. The cabinet may be modified by adding or subtracting fans in the top of the cabinet, inserting or removing panels in the door or adjusting the slide damper in the door, all done externally of the cabinet equipment hardware shelves.
The panels in the front of the cabinet can be manufactured in a clear plexiglass so that lights and other status indicators on the computers are visible through the perforations and the clear blocking panel behind.
It is preferred that all six openings have fans installed at the factory and that temperature responsive controls be employed to control the speed of the fans. Such an arrangement provides maximum flexibility together with the ability to handle maximum as well as minimum heat loads. If for any reason a customer does not desire such an arrangement then a blank panel or panels can be inserted into the unused opening in the top wall to prevent flow of heated air in the room from flowing into the cabinets. As pointed out elsewhere if sufficient flow is induced in the cabinet then a perforated panel can be employed in one of the slots. The type of flow can be induced by convection cooling, then a perforated panel may be used alone or in conjunction with fans carefully adjusted. Cool air can be added from the floor to increase upward flow if the heat is such that the cool air can be heated sufficiently by the equipment to add to the induced flow from outside or is pulled up by fans on the top of the cabinet.
A temperature control and alarm system suitable for use in such a system is sold by Weiss Industries, Farmingdale, N.Y. One such system employs thermistors for sensing temperature network interface circuit, and includes a temperature display. Using this system allows for all of the fans to be factory installed and their speed controlled to maintain temperature.
A manually operated system may also be employed. Initially, all fans are adjusted to desired cabinet operating temperatures and after a short period of time are readjusted to achieve desired results. The temperatures in the cabinets are relatively stable and the display discussed above will warn of any changes needing correction, which will be infrequently.
The use of a structure that permits adjustment of the air flow insures that no more cool air is drawn through the cabinet then is necessary to produce the required cooling. If the heat load is very light no fans may be necessary, and all available openings, as will become apparent, remain in the form of perforated panels and air is in effect pumped through the cabinet by convention currents produced by the heat of the loads inside the cabinet. No opening to the cool air under the floor may be necessary. In prior art systems, as stated above, the electrically powered equipment in the cabinet is fed from an uninterruptable power source (UPS), backed up with direct current batteries. These UPS systems are very expensive and power consumption is carefully scheduled. It is an advantage of the present invention to have a convection cooling mode for the cabinet that does not require any UPS power. If the cooling load is greater, one fan may be employed, (an additional fan provides xe2x80x9cN+1xe2x80x9d redundant operation), together with the grommets adjusted to provide sufficient cooling air flow capacity from below the raised floor. In this manner the cooling requirement is satisfied while simultaneously using a minimum of power, raised floor cooling air flow and static pressure. If redundancy is required, for fault tolerance, an additional fan can be used simultaneously to serve a load. The fans have been sized to allow parallel operation of multiple fans. Solid side panels with grommeted holes for wires extending between adjacent cabinets prevent cooling air from short cycling from a heavily loaded cabinet that is adjacent to a lightly loaded cabinet that is adjacent to a lightly loaded, or empty cabinet. If the heat load is heavy fans may be added and the grommets may be opened further. In consequence of such an arrangement heat loads from 100 watts per cabinet up to over 6000 per cabinet may be accommodated.
An additional control is provided by a highly perforated front door of the cabinet. Air is drawn through the front door which is adapted to receive blank panels, so as to block air flow through various regions of the door whereby to control ambient air mixing with the cooling air. If fans are not used, the panels may not need to be inserted, although in some instances leaving part of the perforated opening obstructed may aid convention cooling. Research has proven that having the entire panel unobstructed hurts convection.
The ability to control the cooling effect as a function of heat load by adding or subtracting fans, varying the speed of the fans, controlling the grommets, and controlling flow through the front door without having to make any interior adjustments or changing basic structure provides a degree of flexibility not previously achievable. Concurrent maintainability is critical to the operators of these mission critical facilities.
Additional features of the system relate to the ability to make the changes with ease (concurrent maintainability). A preferably factory installed bottom shelf of the cabinet is located above the floor a distance that permits ready access to the grommets for adjustments to airflow or wire installations. Air flow blocking solid panels fit into spaces into the top that can otherwise receive panels having fans mounted thereon. Clearance bars residing just under the top of the cabinet prevent equipment from being inserted so close to the fans as to inhibit air flow. Additional adjustment is provided by the highly perforated front door and back panel, if convenient, of the cabinet. With a stand alone cabinet, the side panels may be perforated. Various tiles of the elevated access floor must be left out of the floor installation, saving floor costs and construction time so as to provide unimpeded access of the cabinet to the cooled air and wiring below the elevated floor. In addition, special fixtures are provided to prevent parts of the smaller floor panels from sliding under its associated cabinet, thereby impeding flow into the cabinet.
The above and other features insure that cooling under the floor is employed only when needed and only to the extent necessary to maintain the equipment in the cabinet within the desired temperature range for each piece of equipment. Thus, the desired objective to insure that cooling air and static pressure under the raised floor environment is not wasted by large cuts in the floor to access cables and provide enough space for a mechanic to work. Alternatively, when air is provided from overhead, the induction fans are used to efficiently cool the equipment without sub-cooling the front.
Another distinct advantage of the adjustable grommets is to provide room for a workman to install cables and conduits in the cabinet through the floor and then employ a rotating lid of the grommet for restricting airflow once the cables are installed. A snap in lid to prevent loss can be used, but can easily be removed if necessary for installation and repair work. If additional cooling is required, the grommets can be adjusted without having to move the cabinet.
There are installations in which the site is kept quite cool by air conditioning of the room and under floor cooling is not employed. In such an event the structure is raised above the floor and the access flooring is only used for power and network cabling, not cooling. Under these circumstances it is a violation of National Electric and National Fire Protection Codes to use the access floor for air distribution. The cabinet advantage here is that the induction fans on the top of the cabinet are used to draw room air in from the front, side or back perforated panels. Room air conditioning is used to supplement the ambient cooling effect of the air induced through the cabinet perforated panels. The grommets in the bottom plate remain closed except for those used for power or network cables. Once the wiring and cabling is installed, the grommets are closed down around the cables and wires to avoid wasting airflow from the induction fans and preventing a serious life-safety code violation by inducing airflow through the non-plenum rated access floor. A combination of induction induced flow and fan induced flow may be employed with one or both induced flows employed.
In other installations, the cabinet sits directly on the floor and the power and network cabling is run in cable trays overhead.
The enclosed cabinet concept has distinct advantages in these areas as one of the fan modules can be replaced with a grommet to allow overhead wiring to be routed down into the cabinet top and the grommet rotated to avoid the loss of airflow, while the remaining fan modules remain intact for cooling. If it is preferred to keep all fans in place, the wires can be brought into a fastened slot on the top of the cabinet, next to the fans. Again, room air, supplemented with room air conditioning units, provides the cooling as the room air is induced through the perforated panels of the cabinet. The cables and wiring may now be brought in through the top through a grommet or through a side wall. Convection cooling assists the cooling process; that is, it acts as a pump for moving cool air upward. Room air conditioning supplements the air in the room which is then drawn into the cabinet through the perforated front, side or back walls and directed to the computer equipment of the cabinet.
The concept of bringing in the cables etc. through the top wall may also be applied to the structure employing under floor cooling. One of the panels in the top wall may be replaced with a grommet to provide this feature.
In still another embodiment where under floor air is not employed for cooling but room air conditioning is. The cabinet sits above the floor and fans are inserted in the bottom as well as the top of the cabinet. Since the colder air always falls toward the floor, fans in the bottom of the cabinet blowing upward produce the greatest efficiency in the system.
If the room is air conditioned, take offs from overhead ducts can blow down directly into the cabinets while the fans in both the top and bottom of the cabinets draw air down through the cabinet; the fan on top being removed from the area of the incoming duct as far as the top of the cabinet permits.